This invention relates to films or sheets made of blends of certain amorphous poly(aryl ether ketones) with polyarylates and to laminates of such films or sheets with polyvinyl fluoride (PVF) films or sheets.
Poly(aryl ether ketones) are a well known class of engineering polymers that have outstanding mechanical properties and low flammability. Because of that, they are particularly well suited in certain high value applications, such as, for example, in panels used in aircraft interiors.
Poly(aryl ether ketones) generally are known to fall into three classes, poly(ether ketones) (PEKs), poly(ether ether ketones) (PEEKs), and poly(ether ketone ketones) (PEKKs). PEKKs are a valuable class of poly(aryl ether ketones).
The most commonly commercially available PEKKs contain the following repeating unit (1): ##STR1## where Ph stands for 1,4-phenylene; Ph' stands for 1,3-phenylene; and x and y are positive numbers.
Such PEKKs usually are made, either directly or indirectly, from diphenyl ether and a mixture of terephthalyl (T) chloride and isophthalyl (I) chloride of varying T/I ratios.
Many such PEKKs are described, for example, in U.S. Pat. Nos. 3,516,966 to Berr, 3,767,620 to Angelo et al., 4,816,556 to Gay et al., and 4,720,537 and 4,704,448 to Brugel.
Depending on their T/I ratios, PEKKs are either partly crystalline or amorphous. Crystalline PEKKs have a melting point of about 330.degree. C. or higher. Melt processability of PEKKs also depends to some extent on the T/I ratio, but normally processing temperatures in excess of 300.degree. C. are required.
Polyarylates also are well known. These may be crystalline and frequently anisotropic, exhibiting liquid crystal properties, or amorphous and isotropic. Polyarylates of interest in the present invention are amorphous and isotropic. They are polyesters of dihydroxyaromatic compounds such as, for example, dihydroxybenzenes, 2,2-bis(4-hydroxyphenyl)propane also known as bisphenol A, dihydroxydiphenyls, and dihydroxynaphthalenes and dicarboxylic aromatic acids such as, for example, phthalic acids or naphthalenedicarboxylic acids. A typical polyarylate is one based on bisphenol A and isophthalic acid or a mixture of isophthalic and terephthalic acids. Such polyarylates are described and referenced, among others, in U.S. Pat. No. 4,886,875 to Gay et al. The glass transition temperature (Tg) of polyarylates normally is within the range of about 120-190.degree. C., and they are well melt-processable.
Certain blends of PEKKs with other polymers are known, for example, from U.S. Pat. Nos. 4,816,556 to Gay et al. and 4,720,537 to Brugel. The latter specifically mentions blends of certain PEKKs with polyarylates made from a bisphenol and an aromatic dicarboxylic acid.
European Patent Application 0 170 067 of Union Carbide Corporation discloses blends of a crystalline poly(aryl ether ketone) with a polyarylate and/or a liquid crystalline polyarylate. Those blends are said to have significantly higher notched izod impact strength and tensile impact strength than those of either unblended constituent. This European patent application also reports that addition of liquid crystalline polyarylates unexpectedly decreases melt flow (increases melt viscosity), while U.S. Pat. No. 4,438,236 had earlier stated that addition of small amounts of liquid crystalline polymers to many other polymer systems increased melt flow (decreased melt viscosity).
While many poly(aryl ether ketones), including a number of PEKKs, are crystalline, thermoformable amorphous sheets of certain PEKKs as well as their laminates with polyvinyl fluoride sheets are known. The former are described in the copending patent application Ser. No. 07/283,695 of J. S. Bloom, while the latter are described in her U.S Pat. No. 4,937,135. Such amorphous sheets are made from PEKKs with a properly controlled T/I isomer ratio by quenching extruded sheets at a controlled cooling rate.
Although both the thermoformable PEKK sheets and their laminates with polyvinyl fluoride sheets are of considerable commercial importance, the cost of such sheets is quite high. It thus would be desirable to provide a blend of PEKK with another, less expensive, polymer, which would not impair the outstanding mechanical properties of PEKK and possibly would improve some of its properties or would improve its processability, as compared with PEKK alone.